From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 289A6C2D0B1 for ; Wed, 5 Feb 2020 03:05:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DDB6F2082E for ; Wed, 5 Feb 2020 03:05:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="oLjjl/Qm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727862AbgBEDFJ (ORCPT ); Tue, 4 Feb 2020 22:05:09 -0500 Received: from ozlabs.org ([203.11.71.1]:43509 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727774AbgBEDFI (ORCPT ); Tue, 4 Feb 2020 22:05:08 -0500 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 48C5yp0hsYz9sSR; Wed, 5 Feb 2020 14:05:05 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1580871907; bh=Dy2HNszoS5jMHuHyexeNZ1i6v2XpVUmuydKw/9Caj58=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=oLjjl/QmMaQUGkaI425lp8ZqbybG1H7xgmO+WmWq3t6CGe3Ydfi2omMvBob16Z5TS LHkGOmvtvcpZoOVFbp1xrUN8gFyM+NV2mLZMiM0QNEI7mXLXmjvRfPJAaikuMqME9U DdqyIDLQ8fMvvU9O3fXj+2ZNog4M9YaBI1kKj0vVSxuvesokyfqnXtxONTr0BTRBPw GW6r4NuLz+BlK//+r3+ZzGcMec3ZhTxzZS+gLGPQpEtFPtWSi10F20kXho2mhO2xk1 C2dHxfOWKKQ1nfwjw5I8ncgxAzNir+zHOoAFGWZtbmPWBsUWAIawAKTavRpdoKHRah /1o2zj3OuuW7Q== From: Michael Ellerman To: Dan Williams , linux-nvdimm@lists.01.org Cc: "Aneesh Kumar K.V" , Jeff Moyer , Benjamin Herrenschmidt , Paul Mackerras , vishal.l.verma@intel.com, hch@lst.de, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 2/5] mm/memremap_pages: Introduce memremap_compat_align() In-Reply-To: <158041476763.3889308.13149849631980018039.stgit@dwillia2-desk3.amr.corp.intel.com> References: <158041475480.3889308.655103391935006598.stgit@dwillia2-desk3.amr.corp.intel.com> <158041476763.3889308.13149849631980018039.stgit@dwillia2-desk3.amr.corp.intel.com> Date: Wed, 05 Feb 2020 14:05:02 +1100 Message-ID: <875zgl3fa9.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dan Williams writes: > The "sub-section memory hotplug" facility allows memremap_pages() users > like libnvdimm to compensate for hardware platforms like x86 that have a > section size larger than their hardware memory mapping granularity. The > compensation that sub-section support affords is being tolerant of > physical memory resources shifting by units smaller (64MiB on x86) than > the memory-hotplug section size (128 MiB). Where the platform > physical-memory mapping granularity is limited by the number and > capability of address-decode-registers in the memory controller. > > While the sub-section support allows memremap_pages() to operate on > sub-section (2MiB) granularity, the Power architecture may still > require 16MiB alignment on "!radix_enabled()" platforms. > > In order for libnvdimm to be able to detect and manage this per-arch > limitation, introduce memremap_compat_align() as a common minimum > alignment across all driver-facing memory-mapping interfaces, and let > Power override it to 16MiB in the "!radix_enabled()" case. > > The assumption / requirement for 16MiB to be a viable > memremap_compat_align() value is that Power does not have platforms > where its equivalent of address-decode-registers never hardware remaps a > persistent memory resource on smaller than 16MiB boundaries. > > Based on an initial patch by Aneesh. > > Link: http://lore.kernel.org/r/CAPcyv4gBGNP95APYaBcsocEa50tQj9b5h__83vgngjq3ouGX_Q@mail.gmail.com > Reported-by: Aneesh Kumar K.V > Reported-by: Jeff Moyer > Cc: Benjamin Herrenschmidt > Cc: Paul Mackerras > Cc: Michael Ellerman > Signed-off-by: Dan Williams > --- > arch/powerpc/include/asm/io.h | 10 ++++++++++ > drivers/nvdimm/pfn_devs.c | 2 +- > include/linux/io.h | 23 +++++++++++++++++++++++ > include/linux/mmzone.h | 1 + > 4 files changed, 35 insertions(+), 1 deletion(-) The powerpc change here looks fine to me. Acked-by: Michael Ellerman (powerpc) cheers > diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h > index a63ec938636d..0fa2dc483008 100644 > --- a/arch/powerpc/include/asm/io.h > +++ b/arch/powerpc/include/asm/io.h > @@ -734,6 +734,16 @@ extern void __iomem * __ioremap_at(phys_addr_t pa, void *ea, > unsigned long size, pgprot_t prot); > extern void __iounmap_at(void *ea, unsigned long size); > > +#ifdef CONFIG_SPARSEMEM > +static inline unsigned long memremap_compat_align(void) > +{ > + if (radix_enabled()) > + return SUBSECTION_SIZE; > + return (1UL << mmu_psize_defs[mmu_linear_psize].shift); > +} > +#define memremap_compat_align memremap_compat_align > +#endif > + > /* > * When CONFIG_PPC_INDIRECT_PIO is set, we use the generic iomap implementation > * which needs some additional definitions here. They basically allow PIO